Lateral Snapping Elbow Caused by Entrapment of the Degenerative Annular Ligament: A Case Series.

BACKGROUND

Lateral snapping elbow is a rare condition, and cases attributed to intra-articular lesions of the annular ligament are particularly rare. This study was performed to analyze cases of lateral snapping elbow due to annular ligament entrapment to clarify its pathogenesis and clinical characteristics.

METHODS

We reviewed 4 patients who underwent surgical treatment for painful lateral snapping elbow caused by annular ligament entrapment at 3 institutions from 2010 through 2018. The patients included 2 men and 2 women with a mean age of 59 years (range, 45-69 years). Preoperative evaluations included physical examination, x-rays, magnetic resonance imaging (MRI), and the Mayo Elbow Performance Score (MEPS).

RESULTS

All patients were followed up for an average of 10.5 months (range, 6-12 months). Significant tenderness at the lateral epicondyle of the humerus and snapping were noted preoperatively. MRI consistently demonstrated high signal intensity at the origin of the extensor carpi radialis brevis (ECRB). All 4 patients were diagnosed with snapping elbow associated with lateral epicondylitis, for which surgical intervention was performed because of resistance to conservative treatment. Intraoperatively, the degenerative, entrapped annular ligament within the radiocapitellar joint was observed to reposition during elbow flexion in forearm pronation. Partial resection of the degenerative, entrapped annular ligament was performed, along with ECRB debridement in all patients. The mean MEPS improved from 73.8 preoperatively to 100 postoperatively.

CONCLUSIONS

Degeneration of the annular ligament can lead to its entrapment in the radiocapitellar joint, resulting in snapping elbow. Surgical partial resection of the annular ligament and debridement of the ECRB effectively resolve symptoms and restore function. Snapping elbow caused by annular ligament entrapment may be distinguished by snapping that occurs during pronation and flexion, indicating ligament relocation.